Knee pain can be a result of injury or disease of the knee joint. Injury can affect any of the ligaments, bursae, or tendons surrounding the knee joint. Injury can also affect the ligaments, cartilage, menisci (plural for meniscus), and bones within the joint. The complexity of the design of the knee joint and the fact that it is an active weight-bearing joint are factors in making the knee one of the most commonly injured joints.
Pain can also occur in the knee from diseases or conditions that involve the knee joint, the soft tissues and bones surrounding the knee, or the nerves that supply sensation to the knee area. In fact, the knee joint is one of the most commonly involved joints in rheumatic diseases, including rheumatoid arthritis, reactive arthritis, pseudogout, systemic lupus erythematosus, as well as osteoarthritis. Overuse injury to the knee can lead to inflammation of the tendon below the kneecap (runner's knee or jumper's knee with patellar tendinitis) and bursitis. Trauma can cause dislocation or fracture of the bones of the knee. Diseases that cause knee pain can lead to symptoms and sign such as
- knee swelling,
- joint redness,
- warmth of the knee,
- weakness of the knee,
- crunching or popping noises,
- joint instability,
- inability to straighten the knee,
- joint tenderness, and
- stiffness of the joint.
Many of the symptoms of knee pain can be a result of an excess of fluid forming in the joint.
Other Causes of Knee Pain
- Cartilage Tear
- Bone Tumor (rare)
- Patella Tracking Disorder (Kneecap Misalignment)
- Synovial Plica
- Synovial Sarcoma
Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.Next Article
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Causes of Knee Pain
Ankle Pain (Tendinitis)
Ankle pain is commonly due to a sprain or tendinitis. The severity of ankle sprains ranges from mild (which can resolve within 24 hours) to severe (which can require surgical repair). Tendinitis of the ankle can be caused by trauma or inflammation.
Ankylosing spondylitis is a type of arthritis that causes chronic inflammation of the spine. The tendency to develop ankylosing spondylitis is genetically inherited. Treatment incorporates medications, physical therapy, and exercise.
Aseptic necrosis (avascular necrosis or osteonecrosis) develops when blood supply diminishes to an area of bone and causes bone death. Though aseptic necrosis may be painless, pain is often associated when using the degenerating bone. If caught early, aseptic necrosis may be treated by grafting new bone into the degenerating area. In later stages, joint replacement surgery may be required.
A Baker's cyst, also called a popliteal cyst, is swelling caused by knee joint fluid protruding to the back of the knee (popliteal area of the knee). Not uncommon, Baker's cysts can be caused by virtually any type of joint swelling (arthritis). They are often resolved with removal of excess knee fluid in conjunction with cortisone injections.
Broken Bone (Types of Bone Fractures)
A broken bone is a fracture. There are different types of fractures, such as: compressed, open, stress, greenstick, spiral, vertebral compression, compound, and comminuted. Symptoms of a broken bone include pain at the site of injury, swelling, and bruising around the area of injury. Treatment of a fracture depends on the type and location of the injury.
A bursa is a fluid-filled sac found in the joints that cushions them. Bursitis is an inflammation of the bursae, most commonly caused by repetitive motion. Bursitis can be caused by a bacterial infection and should be treated with antibiotics. Doctors also recommend icing and resting the joint.
Chondromalacia Patella (Patellofemoral Syndrome)
Chondromalacia patella (housemaid's knee or secretary's knee) results from misalignment of the kneecap as it slides over the lower end of the thigh bone. Symptoms include tightness or fullness in the knee area, swelling, and mild discomfort. Treatment includes the use of anti-inflammatory medications, in addition to stretching, strengthening and icing the knee.
Crohn's disease is a chronic inflammatory disease, primarily involving the small and large intestine, but which can affect other parts of the digestive system as well. Abdominal pain, diarrhea, vomiting, fever, and weight loss are common symptoms.
Flatfoot (Pes Planus)
Flatfoot is a disorder in which the foot's entire sole is touching the ground while standing. Symptoms and signs of flatfoot include heel, ankle, knee, hip, and lower back pain and shin splints. Treatment depends upon the type of flatfoot, the symptoms, and the stage of the disorder.
Buildup of uric acid crystals in a joint causes gouty arthritis. Symptoms and signs include joint pain, swelling, heat, and redness, typically of a single joint. Gout may be treated with diet and lifestyle changes, as well as medication.
The joint hypermobility syndrome is a condition in which the joints easily move beyond the normal range expected for a particular joint. The condition tends to run in families. Symptoms of hypermobility syndrome include joint pain. People with hypermobility syndrome are more susceptible to injury, including dislocations and sprains. Anti-inflammatory drugs can help with joint pain. Exercise can strengthen muscles, providing stability.
Iliotibial Band Syndrome
Iliotibial band syndrome is an overuse injury of the thigh and knee. Symptoms include knee pain and possible swelling. Treatment may involve anti-inflammatory medications, physical therapy, ultrasound, massage, using a foam roller at the site of pain, and the use of orthotics.
Juvenile Idiopathic Arthritis (Juvenile Rheumatoid Arthritis)
Juvenile idiopathic arthritis (juvenile rheumatoid arthritis or JRA) annually affects one child in every thousand. There are six types of JIA. Treatment of juvenile arthritis depends upon the type the child has and should focus on treating the symptoms that manifest.
Bursitis of the knee results when any of the three fluid-filled sacs (bursae) become inflamed due to injury or strain. Symptoms include pain, swelling, warmth, tenderness, and redness. Treatment of knee bursitis depends on whether infection is involved. If the knee bursa is not infected, knee bursitis may be treated with ice compresses, rest, and anti-inflammatory and pain medications.
Knee injuries, especially meniscus tears, are common in contact sports. Symptoms and signs of a torn meniscus include knee pain, swelling, a popping sound, and difficulty bending the leg. Treatment may involve resting, icing, compressing, and elevating the knee, in addition to wearing a knee brace, taking anti-inflammatory medications, and stretching the knee.
Lupus (Systemic Lupus Erythematosus or SLE)
Systemic lupus erythematosus is a condition characterized by chronic inflammation of body tissues caused by autoimmune disease. Lupus can cause disease of the skin, heart, lungs, kidneys, joints, and nervous system. When only the skin is involved, the condition is called discoid lupus. When internal organs are involved, the condition is called systemic lupus erythematosus (SLE).
Lyme disease is a bacterial illness, which is spread by ticks when they bite the skin. Initially the disease affects the skin causing a reddish rash associated with flu-like symptoms. It takes weeks to months after the initial redness of the skin for its effects to spread throughout the body. Lyme disease can be treated with antibiotics. Lyme disease can be prevented by using tick avoidance techniques.
Medial Collateral Ligament (MCL) Injury
The medial collateral ligament (MCL) is one of four ligaments that stabilize the knee. MCL injuries are referred to as tears or sprains. Sprains are graded from 1-3 based on the severity of the injury. Symptoms and signs of MCL injuries include swelling, pain, stiffness, and limping. Treatment of MCL injuries may involve resting and bracing the affected knee, and physical therapy can help to restore the range of motion.
Osgood-Schlatter disease, a painful inflammation just below the knee but above the shin, typically affects adolescent boys. Symptoms include localized pain, inflammation, swelling, and calcification. Osgood-Schlatter disease typically goes away over time, however, symptoms can be helped with anti-inflammatory and pain-relieving medications, ice, and rest.
Osteoarthritis is a type of arthritis caused by inflammation, breakdown, and eventual loss of cartilage in the joints. Also known as degenerative arthritis. Osteoarthritis can be caused by aging, heredity, and injury from trauma or disease.
With osteochondritis dissecans, bone and its adjacent cartilage loses its blood supply. Though osteochondritis dissecans can involve any joint's bone and cartilage, elbows and knees are most commonly affected. Though there is no known cure, arthroscopic surgery is frequently performed to remove the damaged cartilage and bone tissue from the joint.
Paget's disease is a chronic bone disorder due to irregular breakdown and formation of bone tissue. Symptoms of Paget's disease include bone pain, headaches and hearing loss, pressure on nerves, increased head size, hip pain, and damage to cartilage of joints.
Psoriatic arthritis is a disease that causes skin and joint inflammation. Symptoms and signs include painful, stiff, and swollen joints, tendinitis, and organ inflammation. Treatment involves anti-inflammatory medications and exercise.
Reactive arthritis is a chronic, systemic rheumatic disease characterized by three conditions, including conjunctivitis, joint inflammation, and genital, urinary, or gastrointestinal system inflammation. Inflammation leads to pain, swelling, warmth, redness, and stiffness of the affected joints. Non-joint areas may experience irritation and pain. Treatment for reactive arthritis depends on which area of the body is affected. Joint inflammation is treated with anti-inflammatory medications.
Rheumatoid Arthritis (RA)
Rheumatoid arthritis (RA) is an autoimmune disease that causes chronic inflammation of the joints, the tissue around the joints, as well as other organs in the body. Because it can affect multiple other organs of the body, rheumatoid arthritis is referred to as a systemic illness and is sometimes called rheumatoid disease. The 16 characteristic early RA signs and symptoms include the following. Anemia Both sides of the body affected (symmetric) Depression Fatigue Fever Joint deformity Joint pain Joint redness Joint stiffness Joint swelling Joint tenderness Joint warmth Limping Loss of joint function Loss of joint range of motion Many joints affected (polyarthritis)
Sarcoidosis, a disease resulting from chronic inflammation, causes small lumps (granulomas) to develop in a great range of body tissues and can appear in almost any body organ. However, sarcoidosis most often starts in the lungs or lymph nodes.
Septic arthritis, or infectious arthritis, is infection of one or more joints by bacteria, viruses, or fungi. Symptoms and signs of septic arthritis include fever, joint pain, chills, swelling, redness, warmth, and stiffness. Treatment involves antibiotics and the drainage of the infected joint.
Sever condition is an inflammation of the growth plate of the bone at the back of the heel where the Achilles tendon attaches. Sever condition can be very painful and is commonly referred to as "growing pains." The condition often disappears with age, but it can also be treated by limiting activity, using antiinflammatory medications, shoe inserts, and heel lifts.
Sickle Cell Disease (Sickle Cell Anemia)
Sickle cell anemia (sickle cell disease), a blood disease which shortens life expectancy, is caused by an inherited abnormal hemoglobin. Symptoms of sickle cell anemia may include bacterial infections, painful swelling of the hands and feet, fever, leg ulcers, fatigue, anemia, eye damage, and lung and heart injury. Treatment for sickle cell anemia aims to manage and prevent the worst manifestations of the disease and focuses on therapies that block red blood cells from stacking together, which can lead to tissue and organ damage and pain.
Sprains and Strains
An injury to a ligament is called a sprain, and an injury to muscle or tendon is called a strain. Sprains and strains may be caused by repetitive movements or a single stressful incident. Symptoms and signs include pain and swelling. Though treatment depends upon the extent and location of the injury, rest, ice, compression, and elevation are key elements of treatment.
Still's disease (systemic-onset juvenile rheumatoid arthritis) is a disorder characterized by inflammation with high fever spikes, fatigue, salmon-colored rash, and/or arthritis. Though there have been several theories regarding the cause(s) of Still's disease, the cause is not yet known. Many symptoms of Still's disease are often treatable with anti-inflammatory drugs.
Torn ACL (Anterior Cruciate Ligament Tear)
The anterior cruciate ligament helps to prevent the top and bottom of the knee from sliding back and forth. Symptoms and signs of a torn ACL include knee pain and swelling. Treatment of a torn ACL depends upon the health of the patient and the patient's expectations and willingness to undertake extensive physical therapy. Rehabilitation after surgical repair of an ACL tear may take more than nine months.
A torn meniscus (knee cartilage) may be caused by suddenly stopping, sharply twisting, or deep squatting or kneeling when lifting heavy weight. Symptoms of a meniscal tear include pain with running or walking long distances, popping when climbing stairs, a giving way sensation, locking, or swelling. Treatment depends upon the severity, location, and underlying disease of the knee joint.
Ulcerative colitis is a chronic inflammation of the colon. Symptoms include abdominal pain, diarrhea, and rectal bleeding. Ulcerative colitis is closely related to Crohn's disease, and together they are referred to as inflammatory bowel disease. Treatment depends upon the type of ulcerative colitis diagnosed.
Vitamin D Deficiency
Vitamin D deficiency has been linked with rickets, cancer, cardiovascular disease, severe asthma in children and cognitive impairment in older adults. Causes include not ingesting enough of the vitamin over time, having limited exposure to sunlight, having dark skin, and obesity. Symptoms include bone pain and muscle weakness. Treatment for vitamin D deficiency involves obtaining more vitamin D through supplements, diet, or exposure to sunlight.
Examples of Medications for Knee Pain
- acetaminophen (Tylenol, Tylenol Arthritis Pain, Tylenol Ext, Little Fevers Children's Fever/Pain)
- aspirin (acetylsalicylic acid, Bayer, Ecotrin, and others)
- celecoxib (Celebrex)
- ibuprofen (Advil, Children's Advil/Motrin, Medipren, Motrin, Nuprin, PediaCare Fever, and others)
- Ketorolac vs. diclofenac
- Ketorolac vs. ibuprofen (Advil)
- Ketorolac vs. naproxen (Aleve)
- naproxen (Aleve, Anaprox, Naprelan, Naprosyn)
- Nonsteroidal Antiinflammatory Drugs (NSAIDs)
- OTC Pain Relievers and Fever Reducers
- rofecoxib, Vioxx
- valdecoxib, Bextra
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